nu shu

"Until recently, women in Jiangyong County were discouraged from learning Nan Shu "men's writing", that is, the Chinese written language. Nü Shu was therefore invented and used secretly, carefully guarded from men. Women learned the writing from their "sworn sisters" and mothers. Sometimes the characters were disguised as decorative marks or as part of artwork. Most of the writing takes a poetic form with lines of verse in 7 characters, or more rarely 5 characters ^[1]. Typical contents of the writings were autobiographies, letters, folk songs, monody, or narration.
The language was suppressed by the Japanese in the 1940s, fearing that the Chinese could use the language to send secret messages. Although Nü Shu has existed for centuries, it was not known to the outside world until recently, when academics "rediscovered" the script in a report to the central government in 1983 . Scholars have since been able to collate only 2000 characters, a fraction of the total. After the Chinese Revolution, literacy spread among women, and Nü Shu fell into disuse and the line of transmission was broken. Also, the Red Guard suppressed Nü Shu during the cultural revolution and destroyed Nü Shu artifacts ^[2]. At present no one living learned Nü Shu from her mother or sworn sisters, though there are a few scholars who learned it from the last of the women who did. After Tang Yueqing made a documentary about Nü Shu, the government of the People's Republic of China started to popularize the effort to preserve this rare writing system, and some younger women are beginning to learn it."
found on wikipedia